Carbohydrate-carbohydrate interaction as a major force initiating cell-cell recognition

Area of Science:

• Evolutionary Biology
• Biochemistry
• Cell Biology

Background:

• Sponges represent the earliest multicellular organisms, offering insights into fundamental biological processes.
• Cell surface proteoglycans mediate crucial cell recognition and adhesion, but their carbohydrate structures are poorly understood.
• Specific carbohydrate-carbohydrate interactions were previously unproven but are hypothesized to be biologically significant.

Purpose of the Study:

• To investigate the existence and characteristics of carbohydrate-carbohydrate interactions in sponge proteoglycans.
• To determine the strength and specificity of these interactions.
• To elucidate the molecular basis of carbohydrate-mediated cell recognition in early metazoans.

Main Methods:

• Atomic force microscopy was used to measure the force of oligosaccharide interactions.
• Species-specificity was assessed through comparative binding studies.
• The role of polyvalency, carbohydrate structure, and Ca(2+)-ions was analyzed.

Main Results:

• Strong carbohydrate-carbohydrate interactions (200-300 pN) were observed between sponge proteoglycan oligosaccharides.
• These interactions demonstrated high species-specificity, mirroring cell-cell recognition.
• Polyvalency, structural diversity, 3D arrangement, and Ca(2+)-ions were identified as key factors.

Conclusions:

• Species-specific carbohydrate-carbohydrate recognition is a fundamental mechanism in cell recognition and adhesion.
• This interaction plays a critical role in the biology of early multicellular organisms like sponges.
• Understanding these interactions provides insights into the evolution of metazoan cell communication.